U.S. patent application number 16/563908 was filed with the patent office on 2021-03-11 for aircraft with bifurcated air inlet.
This patent application is currently assigned to Bell Textron Inc.. The applicant listed for this patent is Bell Textron Inc.. Invention is credited to David Alan Hawthorne, David Frank Haynes, Brad Robert Henson, Steven Ray Ivans, David Lawrence Miller.
Application Number | 20210070461 16/563908 |
Document ID | / |
Family ID | 1000004333899 |
Filed Date | 2021-03-11 |
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United States Patent
Application |
20210070461 |
Kind Code |
A1 |
Ivans; Steven Ray ; et
al. |
March 11, 2021 |
AIRCRAFT WITH BIFURCATED AIR INLET
Abstract
A rotorcraft has a fuselage, an engine disposed substantially
laterally centrally relative to the fuselage, and an air intake
system (AIS). The AIS has a first duct configured to provide
streamline air flow, a second duct configured to provide streamline
air flow, and a combining section configured to receive streamline
air flow from each of the first duct and the second duct. The
combining section is further configured to output streamline air
flow.
Inventors: |
Ivans; Steven Ray; (Ponder,
TX) ; Hawthorne; David Alan; (Colleyville, TX)
; Henson; Brad Robert; (Fort Worth, TX) ; Haynes;
David Frank; (Arlington, TX) ; Miller; David
Lawrence; (North Richland Hills, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bell Textron Inc. |
Fort Worth |
TX |
US |
|
|
Assignee: |
Bell Textron Inc.
Fort Worth
TX
|
Family ID: |
1000004333899 |
Appl. No.: |
16/563908 |
Filed: |
September 8, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B64D 27/14 20130101;
F02C 7/04 20130101; B64D 2033/0226 20130101; B64D 33/02
20130101 |
International
Class: |
B64D 33/02 20060101
B64D033/02; B64D 27/14 20060101 B64D027/14 |
Claims
1. A rotorcraft, comprising: a fuselage; an engine disposed
substantially laterally centrally relative to the fuselage; and an
air intake system (AIS), comprising: a first duct configured to
provide streamline air flow; a second duct configured to provide
streamline air flow; and a combining section configured to receive
streamline air flow from each of the first duct and the second
duct, the combining section further configured to output streamline
air flow.
2. The rotorcraft of claim 1, wherein the combining section is
configured to output the streamline airflow to a compressor of the
engine.
3. The rotorcraft of claim 1, wherein the first duct and the second
duct are substantially symmetrical about a laterally centered plane
of the fuselage.
4. The rotorcraft of claim 1, wherein the first duct and the second
duct extend along paths that comprise primarily lateral directional
changes.
5. The rotorcraft of claim 1, wherein the first duct and the second
duct extend along paths that comprise substantial vertical
direction changes.
6. The rotorcraft of claim 1, the combining section further
comprising: a first upstream unnotched leg portion comprising a
first upstream unnotched leg portion cross-sectional area; and a
second upstream unnotched leg portion comprising a second upstream
unnotched leg portion cross-sectional area that is substantially
the same cross-sectional area as the first upstream unnotched leg
portion cross-sectional area.
7. The rotorcraft of claim 6, the combining section further
comprising: a first downstream unnotched leg portion comprising a
first downstream unnotched leg portion cross-sectional area that is
substantially the same cross-sectional area as the first upstream
unnotched leg portion cross-sectional area.
8. The rotorcraft of claim 7, wherein a cross-sectional shape of
the first downstream unnotched leg portion is different than a
cross-sectional shape of the first upstream unnotched leg
portion.
9. The rotorcraft of claim 6, the combining section further
comprising: a first upstream notched leg portion comprising a first
upstream notched leg portion cross-sectional area, the first
upstream notched leg portion being disposed downstream relative to
the first upstream unnotched leg portion.
10. The rotorcraft of claim 9, wherein a cross-sectional shape of
the first upstream notched leg portion is different than a
cross-sectional shape of the first upstream unnotched leg
portion.
11. The rotorcraft of claim 10, wherein the first upstream notched
leg portion comprises a shallow notch configured to accommodate a
portion of a cylindrical space extending forward from the
engine.
12. The rotorcraft of claim 11, the combining section further
comprising: a first downstream notched leg portion comprising a
deep notch, the deep notch being configured to accommodate a
greater portion of the cylindrical space as compared to the shallow
notch.
13. The rotorcraft of claim 12, the combining section further
comprising: a second downstream notched leg portion comprising a
second downstream notched leg portion cross-sectional area
substantially the same as a first downstream notched leg portion
cross-sectional area of the first downstream notched leg
portion.
14. The rotorcraft of claim 13, the combining section further
comprising: an annular portion configured to receive air from both
the first downstream notched leg portion and the second downstream
notched leg portion.
15. The rotorcraft of claim 14, wherein an annular portion
cross-sectional area of the annular portion is substantially the
same area as the sum of the first downstream notched leg portion
cross-sectional area and the second downstream notched leg portion
cross-sectional area.
16. The rotorcraft of claim 15, wherein the annular portion
cross-sectional area is substantially the same area as an input to
a compressor of the engine.
17. The rotorcraft of claim 1, wherein the engine is substantially
vertically centered relative to the fuselage.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
BACKGROUND
[0003] Current generation tiltrotor aircraft are typically
configured using a dual turbine engine arrangement, with each
engine mounted in wing tip rotating nacelles with rotor,
transmission, exhaust, and other systems. This general arrangement
allows for the efficient integration of engine air induction
systems, where air can be drawn from an external ram air intake,
with minimal distance and duct length needed from ram intake to the
engine compressor inlet. In this arrangement, smooth laminar flow
can be maintained with minimal turbulence and duct friction losses,
thereby maximizing recovery of high dynamic pressure of the
external free stream at the engine compressor inlet. High pressure
recovery (ratio of dynamic air pressure at the compressor plane
divided by the dynamic pressure in the external free stream) is
necessary for maximizing engine power and fuel efficiency, and is a
critical design requirement for achieving high speed and long range
operational objectives with tiltrotor aircraft.
[0004] Many variations of next generation tiltrotor aircraft are
being considered, including single engine configurations with an
engine centered laterally about the fuselage. With this
arrangement, it is necessary to route the air flow path around
gearbox or drive system components located in front of the engine,
and there is typically much greater distance between the engine
inlet compressor and suitable locations for the externally mounted
air intakes, resulting in much longer air ducts and associated
pressure recovery losses.
[0005] Dual intakes for single and multiple engine helicopters are
common, and are typically configured using an air plenum chamber
between the external air intake and the engine inlet compressor.
With this arrangement, the expansion of air upon entry to the
plenum can result in turbulence, circulation, and other losses
contributing to lower pressure recovery at the engine inlet. These
losses contribute to reduced engine power and efficiency. For
typical helicopter speed and range objectives, these losses are
acceptable. However, with more aggressive tiltrotor operational
characteristics noted and for higher performance rotorcraft in
general, these losses have a greater impact and a more efficient
air induction system is needed.
[0006] Many types of tiltrotor aircraft exist, and the engines of
tiltrotor aircraft have been successfully provided in a variety of
locations. Engines of some tiltrotor aircraft have been provided in
rotating nacelles on wings, in stationary locations on wings, and
within fuselages. More recently, some tiltrotor aircraft have been
provided with a single engine located substantially laterally
centered. In some cases, such as when a single laterally centered
engine disposed at least partially within a fuselage is a
turboshaft engine having a compressor with high air input needs,
providing air to the engine is more challenging than when the
engine is located outside the fuselage. More specifically, in
tiltrotor aircraft with a single engine located generally centrally
within the fuselage, routing air ducts to the engine can be
difficult. Routing the air ducts can be especially difficult in
cases where the tiltrotor aircraft is a smaller than typical form
factor, such as, but not limited to, a small unmanned aerial
vehicle (UAV) in which the engine and drive train components are
tightly packaged within the small fuselage. In some cases, it may
be desirable to provide multiple air flow paths to a compressor of
an engine.
[0007] Accordingly, there exists a need for an air intake system
for rotorcraft (both tiltrotor and future helicopters) that can
provide one or more of (1) sufficient air flow to the engine
compressor during operation in a hover flight regime, (2) routing
of air ducts around an obstruction and to a compressor of a
laterally centered engine, and (3) ram air benefits to a compressor
of a laterally centered engine.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Prior Art FIG. 1 is a top view of an aircraft comprising a
conventional air intake system.
[0009] FIG. 2 is a top view of an aircraft comprising an air intake
system according to the disclosure.
[0010] FIG. 3 is a side view of the aircraft of FIG. 2.
[0011] FIG. 4 is a side view of the aircraft of FIG. 2.
[0012] FIG. 5A is a detailed side view of a stow system of the
aircraft of FIG. 2 in a first configuration.
[0013] FIG. 5B is a detailed side view of the stow system of FIG.
5A in a second configuration.
[0014] FIG. 5C is a detailed side view of the stow system of FIG.
5A in a third configuration.
[0015] FIG. 6 is a partial side view of the aircraft of FIG. 2.
[0016] FIG. 7 is a partial top view of the aircraft of FIG. 2.
[0017] FIG. 8 is a partial oblique view of another aircraft
comprising another air intake system according to the
disclosure.
[0018] FIG. 9 is a partial side view of the aircraft of FIG. 8.
[0019] FIG. 10 is a partial top view of the aircraft of FIG. 8.
[0020] FIG. 11 is a partial front view another aircraft comprising
another air intake system according to the disclosure.
[0021] FIG. 12 is a partial top view of the aircraft of FIG.
11.
[0022] FIG. 13 is a detailed top view of the air intake system of
FIG. 11.
[0023] FIG. 14 is a partial cross-sectional view of the air intake
system of FIG. 11 taken along cutting line B-B of FIG. 13.
[0024] FIG. 15 is a partial cross-sectional view of the air intake
system of FIG. 11 taken along cutting line C-C of FIG. 13.
[0025] FIG. 16 is a partial cross-sectional view of the air intake
system of FIG. 11 taken along cutting line D-D of FIG. 13.
[0026] FIG. 17 is a partial cross-sectional view of the air intake
system of FIG. 11 taken along cutting line E-E of FIG. 13.
[0027] FIG. 18 is a partial cross-sectional view of the air intake
system of FIG. 11 taken along cutting line F-F of FIG. 13.
[0028] FIG. 19 is a partial top cutaway view of the air intake
system of FIG. 11.
[0029] FIG. 20 is a top view of a helicopter comprising an air
intake system according to the disclosure.
[0030] FIG. 21 is a side view of the helicopter of FIG. 20.
DETAILED DESCRIPTION
[0031] In this disclosure, reference may be made to the spatial
relationships between various components and to the spatial
orientation of various aspects of components as the devices are
depicted in the attached drawings. However, as will be recognized
by those skilled in the art after a complete reading of this
disclosure, the devices, members, apparatuses, etc. described
herein may be positioned in any desired orientation. Thus, the use
of terms such as "above," "below," "upper," "lower," or other like
terms to describe a spatial relationship between various components
or to describe the spatial orientation of aspects of such
components should be understood to describe a relative relationship
between the components or a spatial orientation of aspects of such
components, respectively, as the device described herein may be
oriented in any desired direction.
[0032] Referring now to Prior Art FIG. 1, an aircraft 10 is shown
that comprises a single engine 12, two air intakes 14, and a plenum
16 configured to mix and homogenize air from the two air intakes
before feeding air to the engine 12. The plenum 16 feature shown
decreases recovered dynamic pressure and results in decreased
engine power and efficiency.
[0033] Referring now to FIG. 2, a top view of an aircraft 100 is
shown according to this disclosure. The aircraft of FIG. 2 does
away with the use of a plenum but retains use of a single engine
tiltrotor. As compared to the aircraft 10, recovered dynamic
pressure, engine power, and engine efficiency can be significantly
increased by substitution of the plenum 16 feature with a more
aerodynamically blended converging section. Key features of the
converging section include smooth flow surfaces without abrupt
changes in duct area and direction along flow path, with symmetric
sections aligned to direct flow evenly to engine inlet compressor.
These features significantly reduce the noted pressure losses
associated with plenum 16, and provide more even flow velocity and
pressure distributions at radial and circumferential locations at
the engine compressor inlet, necessary for meeting allowable
compressor inlet distortions common with high mass flow, axial flow
turbine engines.
[0034] In the embodiment shown, aircraft 100 is a tiltrotor having
a laterally centered plane 101 that, when viewed from above,
divides the aircraft 100 into a left portion and a right portion
(or a port side and starboard side). However, in other embodiments,
aircraft 100 may be any other type of aircraft (e.g. fixed-wing
aircraft, vertical takeoff and landing (VTOL) aircraft, "manned" or
"unmanned" drone, etc.). Aircraft 100 generally comprises a
fuselage 102 and a stowable wing assembly 104 comprising a
selectively rotatable wing body 105 and a plurality of wings 106
extending therefrom. Each wing 106 comprises a pylon 108 comprising
a rotor assembly 110 having a plurality of rotor blades 112 coupled
thereto. Each pylon 108 is selectively pivotable between a
horizontal orientation and a vertical orientation with respect to
the fuselage 102 and associated wing 106 to adjust the thrust angle
and transition the aircraft 100 between an airplane mode and a
helicopter mode. Accordingly, the airplane mode is associated with
a more horizontally-oriented thrust angle and propelling the
aircraft 100 forward in flight, while the helicopter mode is
associated with a more vertically-oriented thrust angle and
propelling the aircraft 100 to and from a landing area.
[0035] Aircraft 100 also comprises a drive component carried in the
fuselage 102. In the embodiment shown, the drive component
comprises an engine 120 coupled to an engine reduction gearbox
("ERGB") 122 comprising a retractable driveshaft 124. However, in
other embodiments, the drive component may comprise a direct-drive
electric motor, a direct-drive engine, a motor and gearbox
combination, or an engine and a redirection gearbox, each
comprising a retractable driveshaft 124. In the embodiment shown,
operation of the engine 120 causes the retractable driveshaft 124
to rotate about its rotation axis 126. The retractable driveshaft
124 is selectively extended and retracted axially along rotation
axis 126 to engage and disengage from an auxiliary or mid-wing
gearbox 130 disposed within the selectively rotatable wing body 105
of the wing assembly 104. The mid-wing gearbox 130 is operatively
coupled to an interconnect driveshaft 132 extending therefrom
through each wing 106 to a pylon gearbox 134 disposed in each pylon
108. Each pylon gearbox 134 is coupled to the associated rotor
assemblies 110 through a rotor mast 136. Thus, when the retractable
driveshaft 124 is engaged with the mid-wing gearbox 130, rotation
of the retractable driveshaft 124 imparted by the engine 120 is
transmitted through the mid-wing gearbox 130 to the interconnect
driveshafts 132 and the rotor masts to impart rotation to the
counter-rotating rotor assemblies 110. Conversely, when the
retractable driveshaft 124 is disengaged from the mid-wing gearbox
130, rotation of the retractable driveshaft 124 will not impart
rotation to the rotor assemblies 110. As such, the retractable
driveshaft 124 allows the engine 120 to operate to run pre-flight
checks, provide electrical power, and/or provide functions of an
auxiliary power unit (APU) without engaging the rotor assemblies
110.
[0036] In some embodiments, aircraft 100 may also comprise a wing
assembly rotation system 140 configured to selectively rotate the
wing assembly 104 with respect to the fuselage 102 about stow axis
142. Most notably, the stow axis 142 is offset from the rotation
axis 126 of the retractable driveshaft 124. More specifically, the
stow axis 142 is displaced longitudinally along a length of the
fuselage 102 with respect to the rotation axis 126 of the
retractable driveshaft 124. In some embodiments, the offset between
the stow axis 142 and rotation axis 126 may be about twelve inches.
The location of the rotation axis 126 is generally set by the
location of the interconnect driveshafts 132 and/or the mid-wing
gearbox 130. The stow axis 142 is generally selected to center the
wing assembly 104 over the fuselage 102, thereby reducing the
overall footprint of the aircraft 100 when the wing assembly 104 is
fully rotated. Further, in some embodiments, offsetting the stow
axis 142 towards a more forward portion of the wing assembly 104
may provide structural benefits, such as allowing rotation of the
wing assembly 104 in a thicker, more structurally rigid portion of
the wing assembly 104. Additionally, as will be discussed further
herein, it will be appreciated that since the retractable
driveshaft 124 extends at least partially into the wing body 105 of
the wing assembly 104 when the retractable driveshaft 124 is
engaged with the mid-wing gearbox 130, the retractable driveshaft
124 is configured to accommodate the misalignment of the
retractable driveshaft 124 and the stow axis 142 by selectively
disengaging from the mid-wing gearbox 130. Accordingly, it will be
appreciated that the gearbox 122 comprising the retractable
driveshaft 124, the mid-wing gearbox 130, and the wing assembly
rotation system 140 may be referred to collectively as a stow
system 150.
[0037] Referring now to FIG. 3, a side view of the aircraft 100 of
FIG. 2 is shown according to this disclosure. Aircraft 100 is shown
with the retractable driveshaft 124 engaged with the mid-wing
gearbox 130 and wing assembly 104 configured in a flight position.
As shown, the retractable driveshaft 124 is selectively extended
vertically to engage the mid-wing gearbox 130 when the wing
assembly 104 is configured in the flight position. Thus, when the
retractable driveshaft 124 is engaged with the mid-wing gearbox
130, rotational motion of the retractable driveshaft 124 imparted
by the engine 120 is transferred through the mid-wing gearbox 130
to the interconnect driveshafts 132 and the rotor masts to impart
rotation to the counter-rotating rotor assemblies 110 to
selectively propel the aircraft 100.
[0038] Referring now to FIG. 4, a side view of the aircraft 100 of
FIG. 2 is shown according to this disclosure. Aircraft 100 is shown
with the retractable driveshaft 124 disengaged with the mid-wing
gearbox 130 and wing assembly 104 configured in a stowed position.
As shown, the retractable driveshaft 124 is selectively retracted
vertically to disengage the mid-wing gearbox 130. After the
retractable driveshaft is disengaged from the mid-wing gearbox 130,
the wing assembly 104 may be selectively rotated relative to the
fuselage 102 about the stow axis 142 in a clockwise direction as
viewed from the top of the aircraft 100 until the wing assembly 104
reaches the stowed position. In the stowed position, it will be
appreciated that the retractable driveshaft 124 is misaligned from
the mid-wing gearbox 130. In some embodiments, the stowed
configuration of the wing assembly 104 may be reached after the
wing assembly 104 is rotated about ninety degrees. Furthermore, in
some embodiments, it will be appreciated that the wing assembly 104
may be rotated relative to the fuselage 102 about the stow axis 142
in a counter-clockwise direction.
[0039] Referring now to FIGS. 5A-5C, detailed side views of the
stow system 150 of the aircraft 100 of FIGS. 2-4 are shown
according to this disclosure. More specifically, FIG. 5A shows the
retractable driveshaft 124 engaged with the mid-wing gearbox 130
and the wing assembly 104 configured in the flight position, FIG.
5B shows the retractable driveshaft 124 disengaged from the
mid-wing gearbox 130 and the wing assembly 104 configured in the
flight position, and FIG. 5A shows the retractable driveshaft 124
disengaged from the mid-wing gearbox 130 and the wing assembly 104
rotated about the stow axis 142 and configured in the stowed
position. It will be appreciated that the retractable driveshaft
124 and the mid-wing gearbox 130 comprise an interface designed to
properly align splines 125 of the retractable driveshaft 124 and
the mid-wing gearbox 130 when the retractable driveshaft 124 is
being selectively extended to engage the mid-wing gearbox 130.
[0040] In operation, the retractable driveshaft 124 is selectively
extended and retracted to engage and disengage from, respectively,
the mid-wing gearbox 130 disposed in the wing body 105 of the wing
assembly 104. The retractable driveshaft 124 may be actuated
electrically, electro-mechanically, hydraulically, and/or
mechanically. For example, in some embodiments, the retractable
driveshaft 124 may be extended and retracted by a rack and pinion.
However, in other embodiments, the retractable driveshaft 124 may
be extended and retracted by a machine screw type system. When the
retractable driveshaft 124 is engaged with the mid-wing gearbox 130
as shown in FIG. 5A, the retractable driveshaft 124 may be
selectively retracted to a retracted position as shown in FIG. 5B.
After the retractable driveshaft 124 is retracted, the wing
assembly 104 may be selectively rotated relative to the fuselage
102 about the stow axis 142 until the wing assembly 104 reaches the
stowed position as shown in FIG. 5C. Once the stow system 150 of
aircraft 100 is configured as shown in FIGS. 4 and 5C, the aircraft
100 may be parked, stowed, and/or driven into an entrance of a
hangar while reducing the overall footprint of the aircraft 100,
thereby allowing for more compact storage of aircraft 100 and
increased storage capacity of multiple aircrafts 100. Furthermore,
from the stowed position shown in FIG. 5C, the wing assembly 104
may be selectively rotated relative to the fuselage 102 about the
stow axis 142 until the wing assembly 104 reaches the flight
position as shown in FIG. 5B. Thereafter, the retractable
driveshaft 124 may be selectively extended to engage the mid-wing
gearbox 130 as shown in FIGS. 3 and 5A, where the aircraft 100 is
configured for flight.
[0041] Referring to FIGS. 2-4, the aircraft 100 further comprises
an air intake system (AIS) 200. To minimize these losses, AIS 200
has air intakes disposed as close to the engine as possible,
minimizes bends and transitions along the air flow path. This is
accomplished by using a dual intake system, symmetrically mounted
on sides of fuselage, ahead of the wing, or at other suitable
locations providing optimal routing of air flow path. FIG. 2 shows
an embodiment for a single engine tiltrotor application. A plenum
feature shown decreases recovered dynamic pressure and results in
decreased engine power and efficiency. These losses can be
significantly reduced by substitution of the plenum feature with a
more aerodynamically blended converging section, as shown in FIG. 3
and FIG. 4. Key features of the converging section include smooth
flow surfaces without abrupt changes in duct area and direction
along flow path, with symmetric sections aligned to direct flow
evenly to engine inlet compressor. These features significantly
reduce the noted pressure losses associated with plenum
arrangement, and provide more even flow velocity and pressure
distributions at radial and circumferential locations at the engine
compressor inlet, necessary for meeting allowable compressor inlet
distortions common with high mass flow, axial flow turbine
engines.
[0042] In the embodiment described in FIGS. 2-5, the intakes are
symmetrically located on the sides of the fuselage, although can be
mounted in other locations such as forward of the wing as shown in
FIG. 8.
[0043] The AIS 200 comprises a plurality of air inlets 202 that
serve as entrances to ducts 204. The ducts 204 are disposed at
least partially within the fuselage 102 and join with each other at
a crotch 206 so that the ducts 204 feed air into a combining
section 208 located generally downstream relative to crotch 206
(and generally aft of the crotch 206). The combining section 208 is
configured to receive streamline air flow from the ducts 204. The
combining section 208 is also configured to allow the air received
from the ducts 204 to continue flowing in a streamline manner (as
opposed to turbulent) from the crotch 206 to an output 210 of the
combining section 208. Air from the output 210 is subsequently fed
to a compressor 121 of the engine 120. The combining section 208 is
sized and shaped so that the combining section 208 does not act
like a plenum in any significant manner. In other words, the
combining section 208 maintains the above-described streamline flow
of air and outputs the streamline flow of air to the compressor
121. By substantially maintaining the streamline flow of air, the
AIS 200 can provide significant ram air benefits when the aircraft
100 is operated in a forward flight regime.
[0044] FIGS. 6 and 7 show more detailed views of the AIS 200. In
this embodiment, the ducts 204 begin at air inlets 202 which extend
from and are offset from the fuselage 102 by a gap distance 212. By
providing the air inlets 202 in this offset manner, slower boundary
layer air is not captured by the air inlets 202 during operation in
the forward flight regime, thereby maximizing the ram air benefits
provided by the AIS 200. Additionally, and with additional
reference to FIGS. 2-4, it can be seen that a variety of components
that do not form a portion of the AIS 200 are disposed laterally
between the ducts 204. For example, portions of the stow system 150
are disposed laterally between the ducts 204. In this embodiment,
the retractable driveshaft 124 is also disposed laterally between
the ducts 204. The ducts 204 generally follow paths that mirror
each other about the laterally centered plane 101, and the paths of
the ducts 204 generally undulate primarily in a lateral manner
without significant vertical changes. The air inlets 202 are
generally disposed vertically so that they are at least partially
at a same height as a portion of the engine 120 or the compressor
121. In alternative embodiments, the air inlets can be provided
substantially flush with the fuselage, thereby creating a lower
pressure area that draws air into the ducts rather than scooping
air from directly impinging air flows.
[0045] Referring now to FIGS. 8-10, a tiltrotor aircraft 300 is
shown that is substantially similar to aircraft 100 but does not
comprise a stow system for rotation of the wings. The tiltrotor
aircraft 300 comprises another embodiment of an AIS 400. The AIS
400 is substantially similar to the AIS 200 insofar as it is
substantially symmetrical about a laterally centered plane of the
aircraft 300 and also provides streamline air flow output. The
aircraft 300 comprises a fuselage 302 and an engine 304 disposed
laterally centered and within the fuselage 302. The AIS 400
comprises air inlets 402, ducts 404, a crotch 406, a combining
section 408, and an outlet 410 that operate substantially similar
to the similarly named components of AIS 200. However, AIS 400
comprises ducts 404 that comprise a substantial variation in path
both vertically and laterally. More specifically, the ducts 404
extend from a location well above the engine 304 and downward to
the engine 304. The air inlets 402 are located side by side at
least partially above the fuselage 302 and at least partially above
the wings 306. This location of air inlets 402 can reduce
visibility of the air inlets 402 from below which can be beneficial
for preventing detection of the tiltrotor aircraft 300 in hostile
environments.
[0046] Referring now to FIGS. 11-19, an alternative embodiment of
an AIS 500 is shown. The AIS 500 is configured to be disposed in an
aircraft, such as aircraft 100, in a manner substantially similar
to the manner in which AIS 200 is disposed within aircraft 100.
FIG. 11 shows a front view of the MS 500 carried by an aircraft
600. The aircraft 600 comprises a fuselage 602, a wing 604, and an
engine 606 disposed in a substantially laterally centered location
that is lower than the wing 604. The engine 606 is configured to
selectively rotate a shaft 608. The AIS 500 is substantially
similar to the AIS 200, is substantially symmetrical about a
laterally centered plane of the aircraft 600, and similarly
provides a streamline air flow output. The AIS 500 comprises air
inlets 502, ducts 504, a crotch 506, a combining section 508, and
an outlet 510 that operate substantially similar to the similarly
named components of AIS 200.
[0047] FIG. 13 shows the combining section 508 in greater detail
and provides cross-sectional cutting lines B-B, C-C, D-D, E-E, and
F-F, the associated cross-sectional views being provided as FIGS.
14-18, respectively. FIG. 13 also includes generalized airflow
streamlines 512 that indicate that air flows into the combining
section 508 via two upstream unnotched leg portions 514, which are
denoted as being disposed along cutting line B-B and shown as FIG.
14. FIG. 14 shows that the upstream unnotched leg portions 514
comprise a cross-sectional area having a substantially rectangular
shape having rounded corners. The cross-sectional area of the
upstream unnotched leg portions 514 comprise a length 516, a width
518 shorter than the length 516, and a cross-sectional area 520
substantially matched to an associated one of the ducts 504.
[0048] FIG. 13 also shows that air flows from the upstream
unnotched leg portions 514 to relatively downstream unnotched leg
portions 522, an example of which is denoted as being disposed
along cutting line C-C and shown as FIG. 15. FIG. 15 shows that the
downstream unnotched leg portions 522 also comprise a substantially
rectangular shape having rounded corners. The downstream unnotched
leg portions can comprise a length 524, a width 526 shorter than
the length 524, and a cross-sectional area 528. Although the
dimensions of the length 524 and width 526 and associated rounded
corners may be different than the length 516 and width 518 and
rounded corners of upstream unnotched leg portion 514,
respectively, the cross-sectional area 528 is substantially the
same value as the cross-sectional area 520.
[0049] FIG. 13 also shows that air flows from the downstream
unnotched leg portions 522 to upstream notched leg portions 530, an
example of which is denoted as being disposed along cutting line
D-D and shown as FIG. 16. FIG. 16 shows that the upstream notched
leg portions 530 comprise a relatively decreasingly rectangular
shape as compared to upstream unnotched leg portion 514 and
downstream unnotched leg portion 522. In this embodiment, the
upstream notched leg portions 530 can comprise a length 532, a
width 534 shorter than the length 532, decreased radius corners 536
(relative to downstream unnotched portions 522), increased radius
corners 538 (relative to downstream unnotched portions 522), a
shallow notch 540, and a cross-sectional area 542. While the shape
of the upstream notched leg portions 530 is different than both the
upstream unnotched leg portions 514 shape and downstream unnotched
leg portions 522 shape, the cross-sectional area 542 is
substantially the same value as the cross-sectional areas 520, 528.
The shallow notch 540 is present to accommodate the substantially
cylindrical space 544 that extends generally forward from the
engine 606 and which accommodates the shaft 608 and/or other
components exterior to combining section 508.
[0050] FIG. 13 also shows that air flows from the upstream notched
leg portions 530 to downstream notched leg portions 546, an example
of which is denoted as being disposed along cutting line E-E and
shown as FIG. 17. FIG. 17 shows that the downstream notched leg
portions 546 comprise a relatively increasingly partial annulus
shape as compared to upstream notched leg portion 530. In this
embodiment, the downstream notched leg portions 546 comprise an at
least partially C-shaped cross-sectional shape. The downstream
notched leg portions 546 comprise a deep notch 548 that can
accommodate a greater portion of the cylindrical space 544 (as
compared to the shallow notch 540). This increased accommodation of
the cylindrical space 544 is necessary as the airflow is being
increasingly laterally centrally directed as air flows toward the
engine 606. While the shape of the downstream notched leg portions
546 is different than the upstream unnotched leg portions 514
shape, the downstream unnotched leg portions 522 shape and the
upstream notched leg portion 530 shape, the cross-sectional area
550 of the downstream notched leg portion is substantially the same
value as the cross-sectional areas 520, 528, 542.
[0051] As air moves downstream past the downstream notched leg
portions 546, the air of each of the mirrored lateral sides of the
combining section 508 are combined into a single annular flow. Most
generally, the airflow is transitioned from two separate but
substantially equal flows of air into a single combined airflow
about a fore-aft location associated with crotch 506. In other
words, airflow is generally provided in two streams forward of the
crotch 506 and airflow is generally provided in a single combined
annular stream aft of the crotch 506. FIG. 13 shows that air flows
from the downstream notched leg portions 546 to annular portions
552, an example of which is denoted as being disposed along cutting
line F-F and shown as FIG. 18. While the annular portions 552
comprise different shapes relative to the portions 514, 522, 530,
546, the annular portions 552 generally comprise a cross-sectional
area 554 substantially equal to two times the area 520, two times
the cross-sectional area 528, two times the cross-sectional area
542, and/or two times the cross-sectional area 550. The annular
portions 552 comprise form a central hole 556 sufficient to
accommodate the cylindrical space 544 therethrough.
[0052] Referring now to FIG. 19, a top cutaway view of the
combining section 508 is shown. FIG. 19 is helpful in illustrating
that the internal surfaces of the combining section 508 are
aerodynamically shaped along the flow path to minimize variations
in cross-sectional area to maintain smooth flow with minimal
distortion and/or losses. In this embodiment, the cross-sectional
area 554 is substantially the same area as an engine 606 air inlet
and/or compressor of the engine 606.
[0053] Referring now to FIGS. 20 and 21, a top view and a side
view, respectively, of a helicopter 1000 are shown. Helicopter 1000
has a rotor system 1002 with a plurality of rotor blades 1004. The
pitch of each rotor blade 1004 can be selectively controlled in
order to selectively control direction, thrust, and lift of
rotorcraft 1000. Rotorcraft 1000 further includes a fuselage 1006,
and anti-torque system 1008, and a tailboom 1010. Rotorcraft 1000
further includes a landing gear system 1012 to provide ground
support for the helicopter 1000. The helicopter further comprises
an engine 1014 connected to an air intake system 1016. The air
intake system 1016 is substantially similar to the AIS 200 at least
insofar as it comprises air inlets 1018, ducts 1020, a crotch 1022,
a combining section 1024, and an outlet 1026 that operate
substantially similar to the similarly named components of AIS 200.
Portions of the rotor system 1002 are not shown in FIG. 20 so that
the location of the AIS 1016 can be more clearly shown.
[0054] At least one embodiment is disclosed, and variations,
combinations, and/or modifications of the embodiment(s) and/or
features of the embodiment(s) made by a person having ordinary
skill in the art are within the scope of this disclosure.
Alternative embodiments that result from combining, integrating,
and/or omitting features of the embodiment(s) are also within the
scope of this disclosure. Where numerical ranges or limitations are
expressly stated, such express ranges or limitations should be
understood to include iterative ranges or limitations of like
magnitude falling within the expressly stated ranges or limitations
(e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater
than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a
numerical range with a lower limit, RI, and an upper limit,
R.sub.u, is disclosed, any number falling within the range is
specifically disclosed. In particular, the following numbers within
the range are specifically disclosed:
R=R.sub.l+k*(R.sub.u-R.sub.l), wherein k is a variable ranging from
1 percent to 100 percent with a 1 percent increment, i.e., k is 1
percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . 50
percent, 51 percent, 52 percent, . . . , 95 percent, 96 percent, 95
percent, 98 percent, 99 percent, or 100 percent. Moreover, any
numerical range defined by two R numbers as defined in the above is
also specifically disclosed.
[0055] Use of the term "optionally" with respect to any element of
a claim means that the element is required, or alternatively, the
element is not required, both alternatives being within the scope
of the claim. Use of broader terms such as comprises, includes, and
having should be understood to provide support for narrower terms
such as consisting of, consisting essentially of, and comprised
substantially of. Accordingly, the scope of protection is not
limited by the description set out above but is defined by the
claims that follow, that scope including all equivalents of the
subject matter of the claims. Each and every claim is incorporated
as further disclosure into the specification and the claims are
embodiment(s) of the present invention. Also, the phrases "at least
one of A, B, and C" and "A and/or B and/or C" should each be
interpreted to include only A, only B, only C, or any combination
of A, B, and C.
* * * * *